An electric power supply is a device or system that is capable of providing electrical energy to a load—typically by converting electrical energy from one form to another to make the energy compatible with the load's requirements. For example, an electric power supply might convert 120 or 240 volt alternating current (“AC”) energy to lower-voltage, regulated direct current (“DC”) energy appropriate for use by an electronic device such as a computer system. Sometimes power supplies are integrated with the devices for which they supply energy. In other applications, power supplies are discrete components and can be internal or external to the load.
It is known to employ redundant power supply schemes in electronic systems for which high availability is necessary. For example, a server computer that hosts a mission-critical application process for an enterprise may be equipped with two or more power supplies in a power-supply redundant arrangement so that the server may continue to operate even if one of the power supplies fails. In such power-supply redundant systems, the plural power supplies in combination have more than enough source energy to drive the load such that, in the event that one or more of the power supplies fails, the remaining power supplies can continue to source sufficient energy the load. The term “redundant power supply system” as used herein is intended to include these and other systems in which plural power supplies are employed to supply power to a load.